31 Oct 2010

The bolt-on rear framework is done; next up is the small hoop at the front. Stylistically it’s coming out okay (I think); a line projected along the front hood intersects the front edge of the engine cover. Once the front is tacked-in, some cardboard will be set down to see how it all looks.

The tricky part is fitting the panels around the rear down-tubes. Done over again it might have been better aesthetically to tip the waistline tubes downward toward the back a bit to make it a bit easier to deal with the curved cover, but not a biggy. The paneling will all be removable, which took some thought; now it’s just a matter of pushing on with the fabrication…

24 Oct 2010

The rear framework is coming along but there’s nothing worth posting – looks very similar to last week. Did make a slight mod, lowering the top rear edge some… you’ll see, and next weekend should see better progress. The rear cover framework should be done. After that’s done, things should move along fairly fast, since there’s little in the way of actual framework fabrication. Of course there’s still plenty of brackets and such: passenger seat mount, seat belt mounts, fire extinguisher mount, high center-mounted tail light bracket, rearview and side mirror mounts, and then of course lots of paneling. A lot more of the paneling will be made removable – as opposed to Kimini – as I’ve learned my lesson about accessibility!

In other news, I, the two beta-builders, and my volunteer copy editor are going to start reviewing the manuscript, starting the laborious but necessary task of sweeping through the chapters to start cleaning up, reorganizing, clarifying, and sometimes deleting unnecessary stuff (sometimes I tend to go off into the weeds, topic-wise…)

17 Oct 2010

So I go to the steel yard to buy two 20′ tubes, requesting they cut them into thirds:

Me: “Hi, I need these two tubes cut into thirds.”
Them: “Okay, that’s two cuts.”
Me: “Okay.”
Them: “That’ll be $2 for the first cut and a $1 for the second.”
Me: “Fine.”
Them: “Wait, you have two pieces.”
Me: “Right.”
Them: “And you want both cut?”
Me: “Yes.”
Them: “Then that’s four cuts.”
Me: “If you put the tubes side-by-side when you cut them, it’s two cuts.”
Them: “No, each time we operate the saw, that’s considered ‘one cut.’ I don’t make the rules.”
Me: “Right, you are operating the saw twice.”
Them: “But you have two tubes.”
Me: “Right…”
Them: “That’s four cuts, so it’s another $2.”
Me: “For operating the saw twice…”
Them: “Right… no, it’s four cuts. I don’t make the rules…”
Me: “Fine…”

Reminds me of the airlines, ask for a pillow and it’s $3; ask for water and they ask if you want it in a cup – a $2 cup.

Anyway… progress continues. Cut off the diffuser frame (I hate cutting parts off the car – such a huge waste in time, effort, and material.) Bent up the lower curved tubes for the lower surface and used a scrap section of 2″ OD 0.062″ wall tube to become the “bumper.” After that was mocked up I got stuck deciding what to do for the top surface of the engine cover and well, it started designing itself. The subtle change probably requires a couple plywood frames to see if it has an abundance of awesomeness, or a bigger pile of “Eew.” You’ll see.

The last picture is at the local park, Midi and his girlfriend, Ginger. They’re both young, slightly crazy dogs.

16 Oct 2010

Had a long conversation with a couple buddies who, well, are seriously concerned for my safety. Not because of a design flaws, but the 800-lb gorilla in the corner of the room, no mention of aerodynamics. Both pointed out that a Lotus Seven has huge aero drag and, with up to about 150 hp, are pretty hard to be “too” dangerous. Escalate that to something like my brother’s Super Stalker with its 240 hp or so, and he’s seeing 140 mph+. Now decrease the drag some and up the hp by another 67%, and my car could become, well, interesting to control, maybe even taking flight like that Mercedes CLR-GTR did. Yes, it was going a lot faster, but also had much better downforce (well, to a point… it did flip, but you know what I mean) Another possibility is getting enough air under the nose under hard acceleration such that steering goes away…

I let them know that I’m aware of this and am already slightly terrified of the car. I’m discovering what a lot of people have found, that at some point in life we finally have the resources to buy/build/rent something that’s potentially beyond our means to control. A perfect case is people who buy a new Corvette ZR1, take it to a trackday event and get way in over their head, usually in a very bad way. Of course, other people can also rightly say that, “That’s what the gas pedal is for. Just because the car can go 200 mph doesn’t mean you have to.” True, but the downforce comments are very valid.

I explained how, though little has been written, a great deal of thought has been going into provisions for downforce in the form of wing mounts and/or an undertray. The incentive to do something comes from driving Kimini at Laguna Seca. Right through Start/Finish is a gradual rise, then a slight turn to the left as the course drops toward Turn one. In my old Datsun 1200, it was a flat-out straight, but in the Mini it was a bit more… interesting, where my foot really wanted to lift off the gas due to the car getting light coming over the crest, it wanting to float out toward the right curb. So that was in Kimini with 190 whp… Now I’ve got the potential to come through there even faster, so it’s serious incentive to think about such matters now.

Mounts will be provided for front and rear wings, in addition to a wing on the top of the cage. Some Stalker owners do just that, with the wing moveable front-to-back in order to adjust balance. At 150+ mph, something’s going to be needed, so the options will be there.

15 Oct 2010

John Tolmie sent this cool sketch, but I told him it would never work because the steering’s on the wrong side. Seriously, between John’s and Mikko Hietanen’s excellent ideas and artistic skills it looks like the styling solution is at hand.

While I have today off, I’m on-call this weekend (24 hrs a day) so it’s unclear how much will get accomplished. Of course, being on-call means having to stay around home, which could also mean having lots of time to work on the car – if there are no calls… we’ll see.

Bought a Halon fire extingusher, along with a set of Miata sun visors. They’re kind of cool because they fold up, slender enough that they can hide behind the windscreen frame (so when they’re flipped up out of the way they don’t look like raised eyebrows…)

10 Oct 2010

Babysat the granddaughter most of the day, but since a few people have requested pictures so they can try their hand at sketches or Photoshop – here you go! More pictures are on the forum if you want to give it a try. The pictures here are smaller than usual so they don’t get clipped when they appear on the forum.

9 Oct 2010

More stylistic flailing about. These are better, but nothing’s caused an “ahah” moment so the trials continue. The first couple shots; I don’t like the upper rear outside corner – it’s too sharp – but I bet it’s great aerodynamically. The second gets rid of the sharp corner but doesn’t look all that much better and drag’s likely higher. The last picture is a suggestion that reader Mikko Hietanen sent in. It’s pretty good, but because he didn’t know the car dimensions, was able to make it look very tidy in an area where the framework extends further back. I kind of like the big rectangular opening, very bold, and will look fine once screen is installed. A couple steps closer – perhaps.

5 Oct 2010

Hmmm, some doubts are creeping around, after I was all full of myself about having made the final decisions on bodywork. I’m sticking with the side vents; I like how they turned out. The rear… yeah well, there might be some more time spent on that. My brother suggested, before trying other things, mocking up a spoiler or small rear wing across the back which seems like a good idea. Of course, keep in mind that the rear paneling needs to be removable for engine access. That’s always the trick, designing in accessibility.

3 Oct 2010

Went round and round on the engine cover and finally made a decision. The conflicting goals are: easy to make, looks good, light, cheap, low drag, and efficiently gets rid of engine heat. Like all styling decisions, it doesn’t accomplish all these goals and will have supporters and detractors – so be it. Yes it’ll be draggy (but how much more than something that’s a PITA to fabricate?), and no doubt some will think “I would have done it different.” But at the end of the day a decision has to be made so things can move forward.

Slots or holes may be put in the rear surface of the rear fenders to lesson drag – but how much will it help? I may ask our aerodynamicist for a final look, no doubt shaking his head. The pictures aren’t flattering because there isn’t a sense of how small the car is. Without that scale it admittedly makes the cover look huge, but it looks much better in person. Hopefully it’ll look okay once the car’s completed. The total vent area is roughly 1.8 sq-ft, so the idea is to make each side vent opening about half that (yes I know it’s not as simple as the open vent area due to fluid dynamics.)

After that, the side vents were sized up – same thing, a decision has to be made and it was. The panel shown is doable with one sheet with one single-plane bend. I’ll mess with the curve on the inlet a bit more, probably curving the top corner back forwards a tad. Is it perfect? What does perfect mean, anyway? Will everyone like it? Hah, I can already hear the heads shaking; I’ll never make everyone happy, but as someone said, how much like a Lotus Seven is the goal? It is its own thing. Builders can do their own thing, but when it’s done, know that people will say, “I would have done it different…”

2 Oct 2010

Accomplished nothing physical on the car but spent a lot of time staring at it, moving things around, clamping wood and cardboard to the car, and the solution – while still fuzzy – is slowly taking shape.

First it was figuring out the diffuser, then how much to tip the engine cover down to meet it, then how much to split them to allow hot engine air out. Then it was noticed that the top of the fiberglass fenders are virtually even with the top of the engine cover, meaning that paneling could cover the entire assembly, engine and tires. Realized that even if the chassis itself is cleaned up at the back end, there’s still all sorts of drag behind those huge rear fenders… which lead to thinking about creating one rear panel that covers the full width of the car, fenders included. Add a gap to let hot air out of the engine area, and air out from the wheel wells.

As things progressed, more and more of the fiberglass fender was getting covered with paneling, and about that time, realized the horizontal panel across the top of the fender could be extended forward. That then lead into the entire side pod/vent/air inlet thing covered months ago. Around and around… it’s possible the fiberglass fenders might be made redundant, though it means the resulting fender edge will probably look more homemade, without a nice return. Still, it’s a potential savings of $240 (plus shipping) so that’s being kept in mind. Doing this with paneling will require bending tubing, but if it’s small enough, a conduit bender should do. We’ll see.

1 Oct 2010

Stared at the back of the car trying to visualize how to pull this off. There’s tons of ways to go, the trick being to make it easy to make with no composite or compound curves. I think some cardboard tabletop scale models will help; the real car’s too large to fumble around with big sheets of floppy cardboard, using up 10 yards of tape in every iteration. The hard part is coming up with something that’s both aesthetically pleasing yet isn’t an aerodynamic mess. For example, in clean air a downward curving back end of the car generates lift, a bad thing. But with the nose, front suspension, windscreen, cage, and me stirring it up, it’s pretty sure that the flow back there’s going to be a turbulent mess, so how much does a downward curving cover matter – I just don’t know.

Then there’s the malaise of having recently attaining the last big milestone, the dyno test, and the mental downer of having no immediate goal to go after, instead dealing with seemingly a million little things. Or maybe it’s just analysis paralysis.